1. Field of the Invention
The invention relates to a method for separating different cropped layers from plated strips, which are plated by roll bonding. More particularly, the cropped material results from shearing the edges and ends of the plated strip at the various stages in their process of manufacture.
2. Description of Related Art
The technique has been known for many years of manufacturing metal strips constituted by two or more layers of different metals or alloys plated over each other by simultaneous hot and/or cold rolling. For example, in the case of aluminium alloys, there is a substantial production of AlMn or AlFe alloy strips plated with AlSi alloy; these strips are destined particularly for the manufacture of brazed heat exchangers, with the plating alloy AlSi acting as the brazing alloy.
Metal strip manufacture generates, at the different stages of this manufacture, relatively large quantities of cropped material or scrap, which are more often than not recycled in the factory itself by being added to the primary metal used for the casting of semi-products. In the case of plated strips comprising different metals or alloys, the direct recycling of the cropped material in the metal furnace in which the casting metal was developed produces an alloy which is different from the starting alloys, and which is not always usable. Attempts have therefore been made to separate the different layers of cropped plated strips in order to allow them to be recycled separately in the production process.
One known method for implementing this separation is to bring the plated cropped material to a temperature somewhere between the melting points of the two metals or alloys to be separated. Such a process is described for example in U.S. Pat. No. 4,203,762 in respect of steel-aluminium plated strips, and in patent applications WO 99/32260 and WO 00/67942 in respect of Al/Mn aluminium alloy strips plated with an AlSi alloy destined for the manufacture of brazed heat exchangers, thermal separation being accompanied by mechanical separation, by abrasion or shearing. A process of this type requires a massive consumption of energy and costly investment in furnaces.
The purpose of the invention is to obtain a separation process that is straightforward, cost-effective and can easily be applied to industrial production.